I live in Winnipeg, Manitoba where it is quite cold for a big majority of the year. I have dabbled with supplements because I get a couple of major colds every year.
I've heard things like you only need 15 minutes of sunshine per day to get your recommended dose of Vitamin D, but I've also heard it can be quite bad for you if you have too much in your system (and it's hard for your body to flush excess amounts).
If there a safe level of Vitamin D supplements where you won't run this risk? I don't drink milk either because I'm lactose intolerant.